X-RAY CRYSTALLOGRAPHIC ANALYSIS OF MUSCLE PROTEINS

这个子项目是利用资源的许多研究子项目之一。 由NIH/NCRR资助的中心拨款提供。对子项目的主要支持 子项目的首席调查员可能是由其他来源提供的， 包括美国国立卫生研究院的其他来源。为子项目列出的总成本可能 表示该子项目使用的中心基础设施的估计数量， 不是由NCRR赠款提供给次级项目或次级项目工作人员的直接资金。 我们收集了扇贝肌球蛋白头部和尾部的晶体数据。根据我们最近对扇贝肌球蛋白头部肌动蛋白分离的、内部解偶联状态(S1)的高分辨晶体结构的研究(Himmel等人，正在准备中；在我们2001年的国际象棋进展报告中)，我们现在已经获得了S1在功率前敲击或启动构象中的2.6A分辨率结构(Gourinath等人，正在准备中)。这两种结构在子域相互作用方面有很大的不同，对这两种结构的比较将提供关于收缩周期不同状态下连接的灵活性的关键信息。到目前为止，还没有关于肌球蛋白尾部任何部分的详细结构的报道。使用国际象棋时以2.6A分辨率收集的数据，我们正在确定扇贝肌球蛋白尾部的一段50个残基的结构，该片段位于肌球蛋白头部附近。尾部的这一区域对肌球蛋白分子的调节特性至关重要(Li等人，正在准备中)。根据过去几年在CHESS上收集的数据，我们还发表了关于原肌球蛋白和纤维蛋白原关键片段的晶体结构的报告。根据我们对原肌球蛋白N端片段的研究(Brown等人，2001)，我们现在已经确定了横纹肌原肌球蛋白的31个残基的C末端片段的结构，它显示出一种不寻常的张开构象。这些结果揭示了肌钙蛋白T的特定识别位置，并阐明了横纹肌独特调节机制的物理基础(Li等人，PNAS，在出版中)。在我们努力了解血液凝结的分子基础时，我们还研究了纤维蛋白原的晶体结构。我们以前报道了牛纤维蛋白原285 kDa主干的4A结构(Brown等人，2000年)，现在已经获得了该分子中央结构域的1.4A分辨率结构(Madrazo等人，2001年)。这种结构有一个引人注目的二聚体界面，这是以前无法可视化的。综上所述，这些结果提高了我们对分子组装成纤维蛋白原凝块的理解。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. We have collected crystal data from both the head and tail regions of scallop myosin. Following our recent study on the high-resolution crystal structure of the actin-detached, internally-uncoupled state of the scallop myosin head (S1) (Himmel, et al., in preparation; reported in our CHESS Progress Report of 2001), we have now obtained a 2.6A resolution structure of S1 in the pre-power stroke or primed conformation (Gourinath, et al., in preparation). Comparison of these two structures, which differ greatly in subdomain interactions, will provide key information on the flexibility of linkages in different states of the contractile cycle. Until now, there has not been a detailed structure reported for any part of the tail of myosin. Using data collected to 2.6A resolution at CHESS, we are determining the structure of a 50-residue-long segment of the scallop myosin tail, located adjacent to the myosin head. This region of the tail is critical for the regulatory properties of the myosin molecule (Li et al., in preparation). Based on data collected at CHESS during the past few years, we have also published reports on crystal structures of key fragments of tropomyosin and fibrinogen. Following our work on an N-terminal fragment of tropomyosin (Brown et al., 2001), we have now established the structure of a 31-residue C-terminal segment of striated-muscle tropomyosin, which shows an unusual splayed conformation. These results reveal a specific recognition site for troponin T and clarify the physical basis for the unique regulatory mechanism of striated muscles (Li et al., PNAS, in press). In our efforts to understand the molecular basis of blood clotting, we have also pursued crystal structures of fibrinogen. We previously reported the 4A structure of the 285 kDa backbone of bovine fibrinogen (Brown et al., 2000), and have now achieved a 1.4A resolution structure of the central domain of the molecule (Madrazo et al., 2001). This structure has a remarkable dimeric interface, which could not previously be visualized. Taken together, these results have improved our understanding of the assembly of the molecule into the fibrinogen clot.